Hope this will help someone. The clutch will melt the assembly and belt do to extreme heat on the 400. The factory (one of the rep's) admitted the 400 works very hard on flat ground when two people are riding, put it off-road and the unit fails. I have removed the engine covers (black plastic) this helps get the heat out and off the clutch. We are installing a EPI high elevation clutch system and testing next week, results to follow. Pretty bad when you have a new unit (4) 2009s and have to prove to the factory that the 400 2 up should have always been a 550 2 up.